From: dgoncz@replikon.net   
      
   I'll start this thread briefly:   
      
   Strong absorbers of microwave radiation, called susceptors, in practice   
   made of fired grit, are found experimentally to agree with theoretical   
   antiresonant absorption models in which the absorption (1/e) distance is   
   small relative to the size of the sample. Absorption peaks at 1/3 the   
   corrected lamba; there is only this single peak.   
      
   Weak absorbers are found experimentally to agree with theoretical node /   
   antinode antenna-based models in which the absorption peaks at 0.5 the   
   corrected lambda (the wavelength within the sample, which may have a   
   refractive index greater than 3) and multiples of that distance, to wit,   
   0.5, 1.0, 1.5, 2.0, etc., and shows a minimum at 0.75 times that lambda,   
   and the corresponding interleaved submultiples of 0.25 times that   
   lambda, to wit, 0.75, 1.25, 1.75, etc.   
      
   The refractive indices of various refractories are known: Clay Brick   
   1.87, Silicon Carbide 3.87, Aluminum Oxide....dang, I forget that one.   
      
   Structurally, furnace linings resist heat escape and may be combined   
   with microwave-non-interactive nonwoven amporphous fill or blanket such   
   as aerogel or alumina sphere fill or even sand.   
      
   Structurally, microwave furnace linings absorb power, and heat, and this   
   is Not A Good Thing. This heating...*may* be minimized by cutting lining   
   slabs to 0.75, 1.25, 1.75, etc. times the corrected lambda, and fitting   
   them into place with moderately elastic nonwoven   
   microwave-mostly-non-interactive blanketing to adjust the fit.   
      
   Functionally, the susceptor in a microwave furnace can of course be a   
   cube, a square slab, a disc, etc.; there are various forms.   
      
   Noting that the Q per distance of sample size is high, the argument to   
   use susceptor cubes is strong; they resonant in 3 out of 3 axes, unlike   
   1 out of 3 axes for a slab or disc.   
      
   Cost concerns are involved as well, but at $16 for a 3 inch disc of 1/4   
   inch thick silicon carbide supplied as a grinding wheel for a lathe, and   
   in the presence of a recently developed carbide to stainless steel   
   brazing method, one might arrange a stainless crucible with bonded   
   susceptor at a reasonable cost.   
      
   However, with cubes of silicon carbide steel smelting additive at   
   thousands of dollars per tonne, that is nearly a dollar per pound,   
   supplied as cubes made from rolled slag...the opportunity to try an   
   intermediate susceptor holder of radiolucent alumina, a handful of such   
   cubes, which are resonant at the 7mm size, and a stainless crucible, in   
   a modified home microwave...was irresistible.   
      
   So I am doing it.   
      
   Me falta los cubos.   
      
   I will report as I progress.   
      
   Today's activity is trimming the furance lining of glazed white clay   
   tile in back to back slabs which will receive aerogel spacers later, to   
   predicting antiresonant sizes, and refitting, and running the oven I   
   have for ten minutes to see how much they heat up...but first I have to   
   see how much they heat up in the condition they are in now, which is cut   
   to fit. I have to start by removing the light bulb in there.   
      
   Cheers,   
      
   Douglas D Goncz   
   Replikon Research   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)